Binocular lens systems

ABSTRACT

An binocular lens system for improving the vision of a patient including first and second ophthalmic lenses. Each of these lenses is adapted for implantation in an eye or to be disposed on or in the cornea. The first lens has a first baseline diopter power for distance vision correction and the second ophthalmic lens has a second baseline diopter power for other than distance vision correction. The ophthalmic lenses may be intraocular lenses which are implanted in the eyes of a patient or has natural lenses or following removal of the natural lenses.

BACKGROUND OF THE INVENTION

[0001] This invention relates to binocular lens systems which compriseophthalmic lenses. The lenses may be adapted for implantation in an eyesuch as intraocular lenses (IOLS) or adapted to be disposed on or in thecornea such as contact lenses or corneal inlays.

[0002] When functioning normally, the natural lens of the eye issomewhat elastic and therefore enables good vision of objects at alldistances. However, when the natural lens is removed as a result ofdisease or injury and replaced with an IOL, the natural ability of theeye to accommodate is lost completely. However, an ability to haveadequate vision at different distances without using spectacles can beprovided by the IOL which is implanted following removal of the naturallens. To this end, the IOL may be multifocal as shown and described, forexample, in Portney U.S. Pat. No. 5,225,858, Roffman et al U.S. Pat. No.5,448,312 or Menezes et al U.S. Pat. No. 5,682,223. Alternatively, theIOL may be of the type which is accommodating in that it can be moved bythe eye itself as shown and described in commonly assigned applicationSer. No. 09/532,910 filed Mar. 22, 2000 or monofocal with a depth offocus feature as shown and described in Portney U.S. Pat. No. 5,864,378.

[0003] Another approach to overcoming loss of accommodation is to useophthalmic lenses, such as contact lenses or IOLS, with differentoptical characteristics for each eye. For example with a system known asmonovision one lens has a distance vision correction power and the otherlens has a near vision correction power. Another example is shown anddescribed in Roffman et al U.S. Pat. No. 5,485,228. It is also known toimplant a distant dominant multifocal IOL in one eye and a near dominantmultifocal IOL in the other eye as disclosed in the January 1999 issueof Clinical Sciences by Jacobi et al entitled “Bilateral Implantation ofAsymmetrical Diffractive Multifocal Intraocular Lenses,” pages 17-23.

[0004] Ophthalmic multifocal lenses can also be provided with some depthof focus. This is shown and described, for example, in Portney U.S. Pat.No. 5,225,858 and Roffman et al U.S. Pat. No. 5,684,560.

[0005] Whether monovision or multifocal ophthalmic lenses are employed,nighttime images may not be the same for both eyes and/or possess halosas when the headlights of an oncoming vehicle are observed. This cansignificantly reduce the ability of the observer to identify and locateobjects near the headlights. For example, halos tend to be created whenthe patient views a distant object through the near vision portion of amultifocal lens, and the greater the add power, the more perceptible isthe halo.

[0006] For example, this is shown and described in commonly assignedapplication Ser. No. 09/302,977 filed on Apr. 30, 1999. This applicationdiscloses a reduced add power multifocal IOL which reduces the effectsof halos. This reduced add power IOL is implanted in a phakic eye inwhich the natural lens has lost some degree of accommodation, i.e. inpartially presbyopic eyes.

[0007] The disclosure of each of the patent applications and patentsidentified herein is incorporated in its entirety herein by reference.

SUMMARY OF THE INVENTION

[0008] New binocular ophthalmic lens systems have been discovered. Thepresent lens systems provide a combined effect of enhancing distance,intermediate and near visual function. In particular, the lens systemsare very effective in enhancing intermediate vision, for example,relative to systems including two identical multifocal lenses. Nearvision comparable to that of the “identical lens” system is provided bythe present lens systems for both the absolute presbyope in a phakicapplication and in a pseudophakic application. Near vision preferably isenhanced for the earlier presbyope in the phakic application compared tothe “identical lens” systems. The size and/or intensity of multifocalhalos preferably is reduced with the present lens systems. Otherimportant advantages are obtained.

[0009] In general, the present lens systems comprise two lenses. Theophthalmic lens systems of this invention may include first and secondlenses for use with, for example, in or on, first and second eyes of apatient, respectively. Each of the first and second lenses has more thanone vision correction power and is therefore multifocal. Although thisinvention is particularly adapted for IOLS, it is also applicable tolenses which can be disposed on or in the cornea such as contact lensesand corneal inlays.

[0010] One lens, the first lens, has a first baseline diopter power fordistance vision correction, and preferably provides the best imagequality for distance or distant objects. The other lens, the secondlens, has a second baseline diopter power for other than distance visioncorrection and preferably has a baseline diopter power which is moremyopic than the first diopter power, more preferably which is forintermediate vision correction. For example, the second baseline powermay be selected such that the distance refraction of the subject inwhose eyes the present lenses are placed is about 1.5 diopters moremyopic than that of the first lens.

[0011] Baseline diopter power is the optical power which provides bestvisual acuity at a given or targeted distance.

[0012] The first lens is biased for distance vision or distance biased.This may be accomplished, for example, by configuring the first lens sothat the best visual acuity provided by the lens is for distant objects,for example, objects at infinity. The first lens provides better visualacuity for objects at infinity than the second lens. Preferably, thefirst lens substantially optimizes visual acuity from distance tointermediate distances. The first lens has a power including a maximumadd power which preferably is less than the add power for full nearvision correction for the patient. Advantageously, the maximum add powerof the first lens is no greater than about an add power for intermediatevision. The power of the first lens preferably varies from about thepower for distance vision to the add power for intermediate vision. Forexample, the maximum add power of the first lens may be no more thanabout 1.5 diopters or about 1.75 diopters. All of the add powers setforth herein are in the spectacle plane. The first lens preferably has apower including a power required for distance vision correction for thepatient.

[0013] The second lens preferably is biased for intermediate vision.This may be accomplished, for example, by configuring the second lens sothat the best visual acuity provided by the second lens is for objectsat intermediate distances. Alternatively, or in addition thereto, thesecond lens provides better visual acuity from intermediate to neardistances than the first lens. Preferably, the second lens enhancesvisual acuity from intermediate to near distances. At least one of thefirst lens and the second lens preferably has a power including anintermediate add power for intermediate vision correction for thepatient and a maximum add power which is less than the add powerrequired for full near vision correction for the patient. Morepreferably, the maximum add power for the second lens, and still morepreferably for both the first and second lenses, is less than the addpower required for full near vision correction for the patient. Thesecond lens advantageously has a maximum add power of any region of thesecond lens no greater than about the intermediate add power.

[0014] The lenses can be made to have the relatively larger ranges ofvision in various ways. For example, this can be accomplished byappropriately splitting the light between distance, intermediate andnear. Thus, the second lens may focus sufficient light to a near focusregion so as to contribute to the second lens providing enhanced visionand better visual acuity from intermediate to near distance.

[0015] Alternatively or in addition thereto, the depth of focus of thezone or zones of the lens which provide intermediate vision correctionmay be appropriately increased to provide the second lens with enhancedvision characteristics from intermediate to near distances. This may beaccomplished, for example, by controlling the aspheric surface design ofthe lenses. More specifically, the first and second lenses may each havea zone with an add power for intermediate vision correction with suchzone having optical aberrations which increase the depth of focus ofsuch zone. In one preferred embodiment, such zones extend radiallyoutwardly and have progressively changing add powers as the zones extendradially outwardly.

[0016] The add powers of the first lens and the second lens preferablyare reduced over what they would be if the lens had the full add powerrequired for near vision correction. The reduced add powerssignificantly reduce the size and/or intensity of multifocal lens halos,such as those halos which occur in any eye because of the relativelylarge add power component, e.g., full near vision add power, found inmany multifocal lens designs.

[0017] In the interest of keeping the add powers low while providingadequate vision quality, preferably the maximum add power of the firstlens is no greater than about the power required for intermediate visioncorrection and the maximum add power of the second lens is less than thefull add power for near vision correction. By way of example, themaximum add power for the first lens may be from about 0.5 diopter toabout 1.75 diopters and is preferably from about 1 diopter to about 1.5diopters. The full or complete near vision correction typically is in arange of about 2.0 diopters or about 2.5 diopters to about 3.0 or morediopters of add power. Thus, the maximum add power of the second lenspreferably is less than about 2.5 diopters of add power, more preferablyless than about 2.0 diopters of add power.

[0018] The first and second lenses are adapted to provide some depth offocus. The first and second lenses preferably provide some depth offocus toward intermediate vision correction.

[0019] Each of the first and second lenses has an optical axis.Preferably the power of the first lens is different at a plurality oflocations radially outwardly of the optical axis of the first lens, andthe power of the second lens is different at a plurality of locationsradially outwardly of the optical axis of the second lens.

[0020] Viewed from a different perspective, the power of each of thefirst and second lenses changes along a power curve, for example, in aradially outward direction from the associated optical axis. The powercurve for the first lens is different from the power curve for thesecond lens. In one useful embodiment of the present invention, thepower curve of the first lens is substantially similar to the powercurve of the second lens except for the difference between the firstbaseline power and the second baseline power. The power curve of thefirst lens may at least contribute to the first lens having good visualacuity from distance to intermediate distances and the power curve ofthe second lens may at least contribute to the second lens having goodvisual acuity from intermediate to near distances. The first lens mayhave a power which varies from about the power required for far visioncorrection to about a power required for intermediate vision correction.The second lens may have a power which varies from a power required forintermediate vision correction or somewhat below intermediate visioncorrection to the power required for greater than intermediate visioncorrection, preferably, however, less than a power required for fullnear vision correction.

[0021] In one preferred embodiment, the first lens has first, second andthird optical zones arranged radially with respect to the optical axisof the first lens with the second zone being intermediate or between thefirst and third zones and having a greater add power than either of thefirst and third zones. The second lens has first, second and thirdoptical zones arranged radially with respect to the optical axis of thesecond lens with the second zone being intermediate or between the firstand third zones and having a greater add power than either of the firstand third zones of the second lens.

[0022] Although the zones can be of various configurations, they arepreferably substantially annular and substantially concentric.Preferably, there are at least two zones. Still more preferably, thereare three or five of the zones with the innermost and outermost of thezones of the first lens having a power for far vision correction and theinnermost and outermost of the zones of the second lens having a powerother than distance vision correction, preferably for substantiallyintermediate vision correction.

[0023] The power in a radial direction can change either gradually orabruptly. In one form of the invention, each of the second zones has apower which is substantially constant.

[0024] IOLS constructed in accordance with this invention may beimplanted following removal of the natural lenses or in phakic eyes, forexample, phakic eyes having some residual accommodation.

[0025] According to one aspect of the method of this invention, firstand second multifocal ophthalmic lenses having different baselinediopter powers are placed on or in the eyes, respectively, of thepatient. The first lens has a first baseline diopter power for distancevision correction and provides better visual acuity for objects atinfinity than the second lens. The second lens has a second baselinediopter power for other than distance vision correction, preferably forabout intermediate vision correction, and provides better visual acuityfor from intermediate to near distances than the first lens. The maximumadd power of the second lens preferably is less than the add powerrequired for near vision correction. In one embodiment, the secondbaseline power is more myopic than the first baseline power. Preferablythe ophthalmic lenses are IOLs and the step of placing includesimplanting the first and second lenses in the eyes, respectively, of thepatient, for example, with the patient's natural lenses in place orafter removal of the patient's natural lenses.

[0026] According to another feature of the method of this invention,first and second multifocal ophthalmic lenses having different baselinediopter powers are placed on or implanted in the eyes, respectively, ofa patient, without removing the patient's natural lenses. Each of thefirst and second lenses has a power which changes along a power curve,with the power curve of the first being substantially similar to thepower curve of the second lens.

[0027] Although the first and second lenses of the present inventionsmay be contacts or corneal inlays, the features of this invention areparticularly adapted for IOLS which can be implanted, respectively, inthe eyes of the patient.

[0028] Any and all features described herein and combinations of suchfeatures are included within the scope of the present invention providedthat the features of any such combination are not mutually inconsistent.

[0029] The invention, together with additional features and advantagesthereof, may best be understood by reference to the followingdescription taken in connection with the accompanying illustrativedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 is a somewhat schematic elevational view of anotherembodiment of an IOL constructed in accordance with this invention whichis particularly adapted for distance-to-intermediate vision.

[0031]FIG. 2 is a view similar to FIG. 1 of one embodiment of an IOLconstructed in accordance with this invention which is particularlyadapted for intermediate-to-near-vision.

[0032]FIG. 3 is a side elevational view of the IOL of FIG. 1.

[0033]FIG. 4 is a somewhat schematic elevational view of anotherembodiment of an IOL constructed in accordance with this invention whichis particularly adapted for distance-to-intermediate vision.

[0034]FIG. 5 is a view similar to FIG. 4 of another embodiment of an IOLconstructed in accordance with this invention which is particularlyadapted for intermediate-to-near vision.

[0035]FIG. 6 is a side elevational view of the IOL of FIG. 4.

[0036]FIG. 7 is a plot of add power of the IOL of FIG. 1 versus radialdistance squared from the optical axis of that IOL.

[0037]FIG. 8 is a plot similar to FIG. 7 for the IOL of FIG. 2.

[0038]FIG. 9 is a plot similar to FIG. 7 for the IOL of FIG. 4.

[0039]FIG. 10 is a plot similar to FIG. 9 for the IOL of FIG. 5

[0040]FIG. 11A is a plot of visual acuity versus add power for the IOLof FIG. 1 when implanted in an eye of a patient after removal of thenatural lens or in the eye of a phakic patient who is an absolutepresbyope with no accommodation.

[0041]FIG. 11B is a plot similar to FIG. 11A for the IOL of FIG. 2 whenimplanted in an eye of a patient after removal of the natural lens or inthe eye of a phakic patient who is an absolute presbyope with noaccommodation.

[0042]FIG. 11C is a plot similar to FIG. 11A for binocular vision whenthe IOLs of FIGS. 1 and 2 are implanted in the eyes, respectively, of apatient after removal of the natural lenses or in the eyes,respectively, of a phakic patient who is an absolute presbyope with noaccommodation.

[0043]FIG. 12A is a plot of visual acuity versus add power for the IOLof FIG. 1 when implanted in an eye of a phakic patient who is an earlypresbyope with 1.5 diopters of residual accommodation.

[0044]FIG. 12B is a plot of visual acuity versus add power for the IOLof FIG. 2 when implanted in an eye of a phakic patient who is an earlypresbyope with 1.5 diopters of residual accommodation.

[0045]FIG. 12C is a plot of visual acuity versus add power for the IOLsof FIGS. 1 and 2 when implanted in the eyes, respectively, of a phakicpatient who is an early presbyope with 1.5 diopters of residualaccommodation.

[0046]FIG. 13A is a plot of visual acuity versus add power for the IOLof FIG. 4 when implanted in an eye of a patient after removal of thenatural lens or in the eye of a phakic patient who is an absolutepresbyope with no accommodation.

[0047]FIG. 13B is a plot similar to FIG. 13A for the IOL of FIG. 5 whenimplanted in an eye of a patient after removal of the natural lens or inthe age of a phakic patient who is an absolute presbyope with noaccommodation.

[0048]FIG. 13C is a plot similar to FIG. 13A for binocular vision whenthe IOLs of FIGS. 4 and 5 are implanted in the eyes, respectively, of apatient after removal of the natural lenses or in the eyes,respectively, of a phakic patient who is an absolute presbyope with noaccommodation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049]FIG. 1 shows a distance-to-intermediate multifocal IOL 11 and FIG.2 shows an intermediate-to-near multifocal IOL 13 which together withthe IOL 11 form a lens pair or ophthalmic lens system for enhancing thevision of a patient. The IOL 11 includes a multifocal lens body or optic15 an optical axis 16 and having powers for a vision correction asdescribed more fully hereinbelow. The IOL 11 also includes generallyradially extending fixation members 17 which, in this embodiment, aresecured to the lens body 15.

[0050] A variety of configurations can be employed for the fixationmembers 17 in order to provide for effective fixation of the IOL 11 inthe eye. If the IOL 11 is to be implanted following removal of thenatural lens from the eye, then any of those configurations known in theart for that purpose may be employed. On the other hand, if the IOL 11is to be implanted without removal of the natural lens from the eye,then the fixation members 17 should be of a configuration andconstruction which will allow the IOL 11 and the natural lens of the eyeto usefully coexist in the eye. In that regard, any of theconfigurations shown by way of example in commonly assigned applicationSer. No. 09/302,977, filed on Apr. 30, 1999 may be employed.

[0051] The IOLs 111 and 113, shown in FIGS. 4 to 6 are very useful whenimplanted without removal of the natural lenses. Such IOLs are describedfurther hereinafter.

[0052] The fixation members 17 may be made of materials of construction,such as polymeric materials, for example, acrylic, polypropylene,silicone, polymethylmethacrylate and the like, many of which areconventionally used in fixation members. In the embodiment shown each ofthe fixation members 17 has the form shown by way of example in FIGS. 1and 3, and this adapts the IOL 11 for implantation in the capsular bagof the eye after removal of the natural lens.

[0053] The lens body 15 may be constructed of rigid biocompatiblematerials such as polymethylmethacrylate (PMMA), or flexible, deformablematerials, such as silicone polymeric material, acrylic polymericmaterial, hydrogel polymeric material and the like, which enable thelens body to be rolled or folded before insertion through a smallincision into the eye. Although the lens body 15 shown in FIG. 1 is arefractive lens body, it may be diffractive if desired.

[0054] As shown in FIG. 3, the lens body 15 has a convex anteriorsurface 19 and a convex posterior surface 21; however, theseconfigurations are merely illustrative. Although the vision correctionpower may be placed on either of the surfaces 19 or 21, in thisembodiment, the anterior surface 19 is appropriately shaped to providethe desired vision correction powers.

[0055] The IOL 13 similarly has a multifocal lens body 23 and fixationmembers 25 suitably joined to the lens body 23. The opticalcharacteristics, and in particular the baseline diopter powers, of thelens bodies 15 and 23 are different as described more specificallyherein below. However, except for the optical characteristics of thelens bodies 15 and 23, the IOLs 11 and 13 may be identical.

[0056] With respect to optical characteristics, it can be seen from FIG.1 that the IOL 11 has a central zone 27 and additional optical zones 29,31, 33 and 35. In this embodiment, the central zone 27 is circular andthe lens body 15 has a circular outer periphery. Also, in thisembodiment, the additional optical zones 29, 31, 33 and 35 are annularand concentric with the central zone 27, and all of these zones arecentered on the optical axis 16.

[0057] With reference to FIG. 7, it can be seen that the central zone 27and the outermost annular zone 35 have a base or baseline diopter powerwhich is the power required by the patient for distance visioncorrection and is considered as a zero add power. It should also benoted that the diopter power variation shown in FIGS. 7 and 8 isapplicable to any point on the surface of the lens bodies 15 and 23,respectively, at a fixed radial distance from the associated opticalaxes. In other words, the power at any given radial distance from theoptical axis 16 is the same, and the power at any given radial distancefrom the optical axis 38 is the same.

[0058] The annular zone 31 has about the first baseline diopter powerrequired for distance vision correction. Although the annular zone 31could have precisely the power required for distance vision correction,i.e. the first baseline diopter power or zero add power, in thisembodiment, the power of the annular zone 31 decreases progressively andslightly from the outer edge of the zone 29 to about the inner edge ofthe zone 33 to provide spherical aberration correction. Thus, althoughthe optical power of the zone 31 does diminish in a radial outwarddirection in this fashion, it nevertheless is considered to be about thepower needed for far or distance vision correction for the patient. Forexample, the vision correction power of the zone 31 may decrease fromthe first baseline diopter power or zero add power to about 0.25 diopterbelow the first baseline diopter power.

[0059] The zones 29 and 33 have greater vision correction power than thezones 27, 31 and 35 and are preferably at or about the power requiredfor intermediate vision correction. In terms of a single power, thepower for intermediate vision correction would be halfway between thebase diopter power and the add power for near vision correction. By wayof example, if the first baseline diopter power is considered to be zeroadd and the add power for near vision correction is considered to be 3diopters, then the power for intermediate vision correction would be 1.5diopters of add power. More broadly, however, the intermediate visioncorrection power may be taken to embrace a zone of from about 0.5diopter to about 1.75 diopters and preferably that zone may be fromabout 1 diopter to about 1.5 diopters. When thus considered, the powerof the zones 29 and 33 would all be add powers for intermediate visioncorrection.

[0060] The vision correction power in the zone 29 reduces progressivelyand slightly in a radial outward direction from an add power forintermediate vision correction such as 1.5 diopters as shown in FIG. 7to a slightly less add power for intermediate vision correction so as toprovide for spherical aberration correction. Again, to correct forspherical aberration, the maximum power of the zone 33 is less than theminimum power of the zone 29 and reduces progressively and slightly in aradial outward direction as shown in FIG. 7. By way of example, thepower of the zone 29 may decrease linearly from about 1.5 diopters toabout 1.25 diopters and the vision correction power of the zone 33 mayreduce linearly in a radial outward direction from about 1.0 diopter toabout 0.75 diopter. Thus, all of the powers of the zones 29 and 33 maybe considered as add powers for intermediate vision correction. Thus, itcan be readily seen from FIG. 7 that the maximum power of any region ofthe first lens body 15 is no greater than about the power forintermediate vision correction.

[0061] The annular areas of the distance correction zones 27, 31 and 35are intended to be larger than the annular areas of the intermediatepower zones 29 and 33. Moreover, there are three of the distance powerzones 27, 31 and 35 and only two of the intermediate vision correctionzones 29 and 33, although other numbers of these zones may be employed,if desired. Thus, a larger surface of the lens body 15 is dedicated tofocusing or directing light to a far focus region than any other focusregion. Accordingly, the IOL 11 provides very good visual acuity fromdistance to intermediate, and provides better visual acuity for objectsat infinity than the IOL 13. The IOL 11 may be considered to beparticularly adapted for, or even optimized for, distance tointermediate vision.

[0062] The lens body 23 of the IOL 13 has a circular outer periphery, anoptical axis 38, a circular central zone 37 and optical zones 39, 41, 43and 45 which are preferably annular and concentric with the central zone37. All of these zones 37, 39, 41, 43 and 45 are centered on the opticalaxis 38. The nature of the optical zones 37, 39, 41, 43 and 45 makes thelens body 23 optically different from the lens body 15, but except forthis the IOLs 11 and 13 may be identical, if desired.

[0063] It can be seen from FIG. 8 that lens body 23 has a secondbaseline diopter power which is different from the first baselinediopter power of lens body 15. In particular, lens body 23 has a secondbaseline diopter power which is not for distance vision correction. Thesecond baseline diopter power is more myopic than the first baselinediopter power. Specifically, the second baseline diopter power of lensbody 23 is at 1.0 diopter, an intermediate vision connection power. Thecentral zone 37, the annular zone 41 and the outer annular zone 45 areat or about this second baseline diopter power. In this embodiment, thepower of the annular zone 41 decreases progressively and slightly fromthe outer edge of the zone 39 to about the inner edge of the zone 43 toprovide spherical aberration correction. Thus, although the opticalpower of the zone 41 does diminish in a radial outward direction in thisfashion, it nevertheless is considered to be at about the secondbaseline diopter power of lens body 23 needed for intermediate visioncorrection for the patient. For example, the vision correction power ofthe zone 41 may decrease from a 1.0 diopters to about 0.75 diopters.

[0064] The zones 39 and 43 have vision correction powers which areincreased relative to the second baseline diopter power of lens body 23,but the increases are lower than the diopter power required for fullnear vision correction. Overall, the use of reduced diopter add power inboth lens bodies 15 and 23 is effective to advantageously reduce thesize and/or intensity of multifocal halos relative to such halos whichoccur using multifocal lens designs employing full near add powers.

[0065] The vision correction power in the zone 39 reduces progressivelyand slightly in a radial outward direction from an add power such as 2.5diopters as shown in FIG. 8 to a slightly less add power, for example ofabout 2.3 diopters, so as to provide for spherical aberrationcorrection. Again, to correct for spherical aberration, the maximumpower of the zone 43 is about the minimum power of the zone 39 andreduces progressively and slightly in a radial outward direction asshown in FIG. 8. By way of example, the power of the zone 43 may reducelinearly in a radial outward direction from about 2.3 diopters to about2.15 diopters.

[0066] Looked at from a different perspective, lens body 15 (power curveshown in FIG. 7) and lens body 23 (power curve shown in FIG. 8) havesubstantially similar, even identical, power curves with the exceptionof the first baseline diopter power of lens body 15, which is fordistance vision correction and the second baseline diopter power of lensbody 23 which is 1.0 diopter myoptic.

[0067] In this embodiment, the IOL 13 has enhanced intermediate-to-nearvision.

[0068] From FIGS. 7 and 8, it is apparent that the maximum powers of anyregion of the IOL 11 and IOL 13 are less than the add power required forfull near vision correction, the latter being an add power whichtypically is greater than 2.5 diopters. Also, the maximum powers of anyregion of the IOL 11 are no greater than about the intermediate visioncorrection power. Conversely, the minimum powers of any region for theIOL 13 is no less than about the intermediate vision correction power.The plots of FIGS. 7 and 8 represent power curves showing how the visioncorrection power of each of the IOLs 11 and 13 changes in a radiallyoutward direction from the optical axes 16 and 38, respectively, and itis apparent that the power curves of FIGS. 7 and 8 are different,particularly with regard to the baseline diopter power of each of thelens bodies 15 and 23. Moreover, this difference in these power curvescontributes to the range of vision and visual acuity characteristics ofIOLs 11 and 13. Except for this difference in baseline diopter power,the power curve of IOL 11 is substantially similar to the power curve ofIOL 13.

[0069] FIGS. 1-3 illustrate one way that this invention may be embodiedin IOLs. However, the invention may also be embodied in ophthalmiclenses which are adapted to be disposed on or in the cornea such ascontact lenses and corneal inlays. The lens bodies 15 and 23 of FIGS. 1and 2 may also be considered as schematically representing contactlenses or corneal inlays. Of course, these latter two forms ofophthalmic lenses do not have the fixation members 17 or 25.

[0070] This invention also provides a method of correcting the vision ofa patient which comprises placing first and second multifocal ophthalmiclenses on or in the eyes of a patient with the first lens being distancebiased and providing better visual acuity for objects at infinity thanthe second lens. The second lens may be considered near biased andprovides better visual acuity from intermediate-to-near distances thanthe first lens. The maximum power of the second lens preferably is lessthe add power required for full near vision correction for the patient.With specific reference to the embodiments shown in FIGS. 1-3, themethod includes implanting the IOLs 11 and 13 in the eyes, respectively,of the patient. This implantation may occur with the natural lens inplace or may follow the removal of the natural lens from the eye.

[0071] In the event the natural lens is removed, IOL 11 is implanted inthe capsular bag with the fixation members 17 in contact with thecapsular bag. The IOL 13, which has optical characteristics differentfrom the IOL 11, is similarly implanted in the other eye, with thenatural lens removed, of the patient.

[0072] FIGS. 11A-C and 12A-C are of use in gaining a furtherunderstanding of how the IOLs 11 and 13 work. FIGS. 11A-C arethrough-focus-acuity charts for a pseudophakic patient (with no naturalaccommodation) or a phakic patient who is an absolute presbyope with noaccommodation with these IOLs implanted. FIGS. 12A and C arethrough-focus-acuity charts for a phakic patient who is an earlypresbyope with 1.5 diopters of residual accommodation with these IOLsimplanted. Each of these figures shows visual acuity (VA) along theordinate and add power in diopters along the abscissa. In addition, thecorresponding object distance, the reciprocal of the diopter add powerin meters, is also shown along the abscissa. The add power is the addpower required by a patient with no accommodation at the correspondingdistance indicated on the abscissa. The units for visual acuity or VAare Regan. A visual acuity of about 8 corresponds to 20/20 and isconsidered normal vision. Functional vision is considered to be about20/30 up to nearly 20/20, and is shown by the cross hatched or dashedline enclosed band in FIGS. 11A-C and 12A-C. Although functional visionis clinically not normal, it may seem normal to the patient. Below about20/30 vision becomes progressively more difficult and somewhere about 3Regan or slightly worse than 20/60 there is essentially no usable visualacuity. The visual acuity plots of FIGS. 11A-C and 12A-C aretheoretical.

[0073] The IOL 11 (FIGS. 11A and 12A) has better visual acuity atinfinity than does the IOL 13 (FIGS. 11B and 12B) as shown by the highervisual acuity at the ordinate. By comparing FIGS. 11A to 11B and FIGS.12A to 12B, it can be seen that the IOL 13 provides better visual acuityfrom intermediate to near distance than does IOL 11 and that visualacuity in this range is enhanced. Also, by comparing these figures, itcan be seen that the IOL 13 provides better visual acuity for objects atnear distances than the IOL 11.

[0074] The binocular visual acuity remains functional or better fordistance and intermediate objects. In addition, near reading between 40centimeters and 33 centimeters is functional or better. Thus, thepatients should perform all tasks well.

[0075] Another important benefit of the use of different IOLs 11 and 13relates to suppression. As used herein, “suppression” is defined as thebetween-eye-visual acuity difference normalized to the visual acuitydifference for a monovision patient with 2.5 diopters of prescriptiondisparity. A suppression level of 1.0 indicates a full monovision visualacuity difference. It is believed, based on a brief review of theliterature, that a majority of patients will not tolerate a suppressionof 1.0. However, approximately 50% of the patients will tolerate asuppression level of 0.6.

[0076]FIGS. 11c and 12 c include a graph of suppression for IOLs 11 and13. These IOLs when used together provide a suppression level of 0.4 orless, which is advantageously likely to be well tolerated by asubstantial majority of the patients.

[0077]FIG. 4 shows a distance-to-intermediate multifocal IOL 111 andFIG. 5 shows an intermediate-to-near multifocal IOL 113 which togetherwith the IOL 111 form a lens pair or ophthalmic lens system forenhancing the vision of a patient. The IOL 111 includes a multifocallens body or optic 115, an optical axis 116 and has powers for a visioncorrection as described more fully hereinbelow. The IOL 111 alsoincludes generally radially extending footplate-type fixation members117 and 118 which, in this embodiment, are integral with the lens body115 such that the IOL 111 is one piece.

[0078] If the IOL 111 is to be implanted without removal of the naturallens from the eye, i.e. in an early presbyope, then the fixation members117 and 118 should be of a configuration and construction which allowthe IOL 111 and the natural lens of the eye to usefully coexist in theeye. In that regard, the configuration shown in FIG. 4 may be employed.The IOL may be fixated to the iris of the eye, may be located in theanterior chamber of the eye and/or may be fixated at the sulcus of theeye. The fixation members 117 and 118 may be made of materials ofconstruction, such as polymeric materials, for example, acrylic,polypropylene, silicone, polymethylmethacrylate and the like, many ofwhich are conventionally used in fixation members. In the embodimentshown each of the fixation members 117 and 118 has the form shown by wayof example in FIGS. 4 and 6, and this adapts the IOL 111 forimplantation in the anterior chamber of the eye without removal of thenatural lens.

[0079] As shown in FIG. 6, the lens body 115 has a convex anteriorsurface 119 and a substantially plano posterior surface 121; however,these configurations are merely illustrative. Although the visioncorrection power may be placed on either of the surfaces 119 or 121, inthis embodiment, the anterior surface 119 is appropriately shaped toprovide the desired vision correction powers.

[0080] The IOL 113 similarly has a multifocal lens body 123 and fixationmembers 125 and 126 suitably joined to the lens body 123. The opticalcharacteristics and, in particular the baseline diopter powers, of thelens bodies 115 and 123 are different as described more specificallyhereinbelow. However, except for the optical characteristics of the lensbodies 115 and 123, the IOLs 111 and 113 may be identical.

[0081] With respect to optical characteristics, it can be seen from FIG.4 that the IOL 111 has a central zone 127 and additional optical zones129, 131, 133 and 135. In this embodiment, the central zone 127 iscircular and the lens body 115 has a circular outer periphery. Also, inthis embodiment, the additional optical zones 129, 131, 133 and 135 areannular and concentric with the central zone 127, and all of these zonesare centered on the optical axis 116.

[0082] With reference to FIG. 9, it can be seen that the central zone127 and the outermost annular zone 135 have a base diopter power whichis the power required by the patient for distance vision correction andis considered as a zero add power. It should also be noted that thediopter power variation shown in FIGS. 9 and 10 is applicable to anypoint on the surface of the lens bodies 115 and 123, respectively, at afixed radial distance from the associated optical axes. In other words,the power at any given radial distance from the optical axis 116 is thesame, and the power at any given radial distance from the optical axis138 is the same.

[0083] The annular zone 131 has about the first baseline diopter powerrequired for distance vision correction. Although the annular zone 131could have precisely the power required for distance vision correction,i.e. zero add power, in this embodiment, the power of the annular zone131 decreases progressively and slightly from the outer edge of the zone129 to about the inner edge of the zone 133 to provide sphericalaberration correction. Thus, although the optical power of the zone 131does diminish in a radial outward direction in this fashion, itnevertheless is considered to be about the power needed for far ordistance vision correction for the patient. For example, the visioncorrection power of the zone 131 may decrease from a zero add power toabout 0.25 diopter below the base diopter power.

[0084] The zones 129 and 133 have greater vision correction power thanthe zones 127, 131 and 135 and are preferably at or about the powerrequired for intermediate vision correction. More broadly, however, theintermediate vision correction power may be taken to embrace a zone offrom about 0.5 diopter to about 1.75 diopters. When thus considered, thepower of the zones 129 and 133 would all be add powers for aboutintermediate vision correction. In addition, the add power of zones 129and 133 are somewhat greater than the add powers of zones 29 and 33(FIG. 7), respectively.

[0085] If desired, the zone 129 and 133 can have optical powersapproaching add powers required for full near vision correction. Thisembodiment is shown in the shadow or dotted lines in FIG. 9, with thezones shown as 129′ and 133′. Such a higher add power embodiment isadvantageous for patients who require near vision correction, even atthe expense of the presence or occurrence of halos and other nighttimeimages of somewhat increased size and/or intensity.

[0086] The vision correction power in the zone 129 reduces progressivelyand slightly in a radial outward direction from an add power forintermediate vision correction such as about 2 diopters as shown in FIG.9 to a slightly less add power for intermediate vision correction so asto provide for spherical aberration correction. Again, to correct forspherical aberration, the maximum power of the zone 133 is about theminimum power of the zone 129 and reduces progressively and slightly ina radial outward direction as shown in FIG. 9. By way of example, thepower of the zone 129 may decrease linearly from about 2 diopters toabout 1.8 diopters and the vision correction power of the zone 133 mayreduce linearly in a radial outward direction from about 1.8 diopters toabout 1.55 diopter. Thus, all of the powers of the zones 129 and 133 maybe considered as add powers for near or intermediate vision correction.

[0087] The annular areas of the distance correction zones 127, 131 and135 are intended to be larger than the annular areas of the intermediatepower zones 129 and 133. Moreover, there are three of the distance powerzones 127, 131 and 135 and only two of the near or intermediate visioncorrection zones 129 and 133, although other numbers of these zones maybe employed, if desired. Thus, a larger surface of the lens body 115 isdedicated to focusing or directing light to a far focus region than anyother focus region. Accordingly, the IOL 111 provides very good visualacuity from distance to intermediate, and provides better visual acuityfor objects at infinity than the IOL 113. The IOL 111 may be consideredto be particularly adapted for, or even optimized for,distance-to-intermediate vision.

[0088] The lens body 123 of the IOL 113 has a circular outer periphery,an optical axis 138, a circular central zone 137 and optical zones 139,141, 143 and 145 which are preferably annular and concentric with thecentral zone 137. All of these zones 137, 139, 141, 143 and 145 arecentered on the optical axis 38. The nature of the optical zones 137,139, 141, 143 and 145 makes the lens body 123 optically different fromthe lens body 115, but except for this the IOLs 111 and 113 may beidentical, if desired.

[0089] It can be seen from FIG. 10 that the lens body 123 has a secondbaseline diopter power which is different from the first baselinediopter power of lens body 115. In particular, lens body 123 has asecond baseline diopter power which is not for distance visioncorrection. The second baseline diopter power is more myopic than thefirst baseline diopter power. Specifically, the second baseline diopterpower of lens body 123 is at 1.0 diopters, intermediate visioncorrection power. The center zone 137, the annular zone 141 and theouter annular zone 145 are at or about this second baseline diopterpower. In this embodiment, the power of the annular zone 141 decreasesprogressively and slightly from the outer edge from the zone 139 toabout the inner edge of the zone 143 to provide spherical aberrationcorrection. Thus, although the optical power of the zone 141 doesdiminish in a radial outward direction in this fashion, it neverthelessis considered to be at about the second baseline diopter power of lensbody 123 needed for intermediate vision correction for the patient.

[0090] The zones 139 and 143 have vision correction powers which areincreased relative to the second baseline diopter power of lens body123, but are lower than the diopter power required for full near visioncorrection. The use of reduced diopter add powers in both lens bodies115 and 123 is effective to advantageously reduce the size and/orintensity of multifocal halos relative to such halos which occur usingmultifocal lens designs employing full near diopter add powers. The addpowers of zones 139 and 143 relative to the second baseline diopterpower of lens body 123 are different, in particular reduced, compared tothe add powers of zones 129 and 133 relative to the first baselinediopter 115. These features of lens bodies 115 and 123 distinguish themfrom lens bodies 15 and 23 (FIGS. 7 and 8) in which, except for thedifference in baseline diopter powers, the power curves of lens bodies15 and 23 are substantially similar.

[0091] The vision correction power of the zone 139 reduces progressivelyand slightly in a radial outward direction from an add power such as 2.5diopters as shown in FIG. 10 to a slightly less add power, for exampleof about 2.3 diopters so as to provide for spherical aberrationcorrection. Again, to correct for spherical aberration, the maximumpower of the zone 143 is about the minimum power of the zone 139 andreduces progressively and slightly in a radial outward direction asshown in FIG. 10. By way of example, the power of the zone 143 mayreduce linearly in a radial outward direction from about 2.3 diopters toabout 2.15 diopters.

[0092] In this embodiment, the IOL 113 has enhanced intermediate-to-nearvision.

[0093] The plots in FIGS. 9 and 10 represent power curves showing howthe vision correction power of each of the IOLs 111 and 113 changes in aradially outward direction from the optical axis 116 and 138,respectively, and it is apparent that the power curves of FIGS. 9 and 10are different, particularly with regard to the baseline diopter power ofeach of the lens bodies 115 and 123. The differences in these powercurves contribute to the range of vision and vision acuitycharacteristics of IOLs 111 and 113.

[0094] It should be noted that the lens bodies 115 and 123 of FIGS. 4and 5 may also be considered as schematically representing contact lensor corneal inlays. Of course these latter two forms of ophthalmic lensesdo not have the fixation members 117 or 125.

[0095] The IOLs 111 and 113 are particularly adapted to be implanted inanterior chambers of eyes.

[0096]FIGS. 13a-c are of use in gaining a further understanding of howthe IOLs 111 and 113 work. FIGS. 13a-c are through-focus acuity chartsfor a pseudophakic patient, with no natural accommodation, or a phakicpatient who is an absolute presbyope with no accommodation, with theseIOLs implanted.

[0097] The IOL 111 (FIG. 13a) has better vision acuity at infinity thandoes the IOL 113 (FIG. 13b) as shown by the higher vision acuity at theordinate. By comparing FIGS. 13a to 13 b, it can be seen that IOL 113provides better vision acuity for intermediate to near distances thandoes IOL 111 and that vision acuity in this range is enhanced.

[0098] The binocular vision acuity remains functional or better fordistance and intermediate objects. In addition, near reading between 40cm and 33 cm is acceptable. Thus the patients should perform all taskswell.

[0099] In addition, the suppression level shown in FIG. 13c is, overall,reduced relative to the suppression levels obtained using thecombination of IOLs 11 and 13 (see FIGS. 11c and 12 c). This reducedsuppression level of the combination of IOLs 111 and 113 is believed toresult from the difference in add powers between lens bodies 115 and123. As noted previously, the add powers, relative to the baselinediopter powers, of lens bodies 15 and 23 are substantially similar. Thereduced suppression level shown in FIG. 13c indicates that thecombination of IOLs 111 and 113 is advantageously likely to be welltolerated by a large majority of the patients.

[0100] While this invention has been described with respect to variousspecific examples and embodiments, it is to be understood that theinvention is not limited thereto and that it can be variously practicedwithin the scope of the following claims.

What is claimed is:
 1. An ophthalmic lens system for improving thevision of a patient comprising: a first multifocal ophthalmic lens foruse with one eye of a patient; and having a first baseline diopter powerfor distance vision correction; a second multifocal ophthalmic lens foruse with the other eye of the patient, and having a second baselinediopter power for other than distance vision correction and a maximumpower less than the add power required for full near vision correctionfor the patient; and each of said first and second lenses being adaptedfor implantation in an eye or to be disposed on or in a cornea of aneye.
 2. An ophthalmic lens system as defined in claim 1 wherein thesecond baseline diopter power is more myopic than the first baselinepower.
 3. An ophthalmic lens system as defined in claim 1 wherein thesecond baseline diopter power is for intermediate distance correction.4. An ophthalmic lens system as defined in claim 1 wherein at least oneof the first lens and the second lens has a power including anintermediate add power for intermediate vision correction for thepatient and a maximum add power which is less than the add powerrequired for full near vision correction for the patient.
 5. Anophthalmic lens system as defined in claim 4 wherein the maximum addpower of any region of the second lens is no greater than about theintermediate add power.
 6. An ophthalmic lens system as defined in claim4 wherein the maximum add power of any region of the first lens is nogreater than about the intermediate add power.
 7. An ophthalmic lenssystem as defined in claim 1 wherein both the first lens and the secondlens have a maximum add power which is less than the add power requiredfor full near vision correction for the patient.
 8. An ophthalmic lenssystem as defined in claim 1 wherein the second lens provides bettervisual acuity from intermediate to near distances than the first lens.9. An ophthalmic lens system as defined in claim 1 wherein each of thefirst and second lenses has an optical axis, the power of each of thefirst and second lenses changes along a power curve in a radiallyoutward direction from the associated optical axis and the power curvefor the first lens is substantially similar to the power curve for thesecond lens.
 10. An ophthalmic lens as defined in claim 1 wherein eachof the first and second lenses has an optical axis, the power of each ofthe first and second lenses changes along a power curve in a radiallyoutward direction from the associated optical axis and the power curvefor the first lens is different from the power curve of the second lens.11. An ophthalmic lens system as defined in claim 10 which provides areduced level of suppression relative to a similar lens combination withlenses having substantially similar power curves.
 12. An ophthalmic lenssystem as defined in claim 1 wherein the first lens provides bettervisual acuity for objects at infinity than the second lens.
 13. Anophthalmic lens system as defined in claim 1 wherein the second lens hasa zone with an intermediate add power for intermediate vision correctionand the zone has optical aberrations which increase the depth of focusof the zone.
 14. An ophthalmic lens system as defined in claim 13 hereinthe zone extends radially outwardly and has progressively increasingpowers as the zone extends radially outwardly.
 15. An ophthalmic lenssystem as defined in claim 1 wherein the first and second lenses areintraocular lenses.
 16. An ophthalmic lens system as defined in claim 1wherein the first and second lenses are selected from the groupconsisting of contact lenses and corneal inlays.
 17. An ophthalmic lenssystem for improving the vision of a patient comprising: a firstmultifocal ophthalmic lens for use with one eye of a patient, the firstlens having a power including a first baseline diopter power fordistance vision correction for the patient; a second multifocalophthalmic lens for use with the other eye of the patient, the secondlens having a second baseline diopter power other than for distancevision correction, a power including an intermediate add power forintermediate vision correction for the patient and a maximum power whichis less than the full add power required for near vision correction forthe patient; the first lens providing better visual acuity for objectsat infinity than the second lens; and each of the first and secondlenses being adapted for implantation in an eye or to be disposed on orin a cornea of an eye.
 18. An ophthalmic lens system as defined in claim17 wherein the second baseline diopter power is more myopic than thefirst baseline power.
 19. An ophthalmic lens system as defined in claim17 wherein the second baseline diopter power is for intermediatedistance correction.
 20. An ophthalmic lens system as defined in claim17 wherein the maximum add power of any region of the second lens is nogreater than about the intermediate add power.
 21. An ophthalmic lenssystem as defined in claim 17 wherein the maximum add power of anyregion of the first lens is less than the full add power required fornear vision correction of the patient.
 22. An ophthalmic lens system asdefined in claim 17 wherein the maximum add power of any region of thefirst lens is no greater than about the intermediate add power.
 23. Anophthalmic lens system as defined in claim 17 wherein the second lens isbiased for near vision correction for the patient.
 24. An ophthalmiclens system as defined in claim 17 wherein each of the first and secondlenses has an optical axis, the power of each of the first and secondlenses changes along a power curve in a radially outward direction fromthe associated optical axis and the power curve for the first lens issubstantially similar to the power curve for the second lens.
 25. Anophthalmic lens as defined in claim 17 wherein each of the first andsecond lenses has an optical axis, the power of each of the first andsecond lenses changes along a power curve in a radially outwarddirection from the associated optical axis and the power curve for thefirst lens is different from the power curve of the second lens.
 26. Anophthalmic lens system as defined in claim 25 which provides a reducedlevel of suppression relative to a similar lens combination in which thepower curves of the first and second lens are substantially similar. 27.An ophthalmic lens system for improving the vision of a patientcomprising: a first multifocal lens for use with one eye of the patient,the first lens having a first optical axis and a first baseline diopterpower for distance vision correction, the power of the first lenschanges along a first power curve in a radially outward direction fromthe first optical axis; a second multifocal lens for use with the othereye of the patient, the second lens having a second optical axis and asecond baseline diopter power for other than distance vision correction,the power of the second lens changes along a second power curve in aradially outward direction from the second optical axis; the first andsecond power curves being substantially similar; and each of the firstand second lenses being adapted for implantation in an eye or to bedisposed on or in a cornea of an eye.
 28. An ophthalmic lens system ofclaim 27 wherein the maximum add power of any region of the second lensis less than the full add power required for near vision; and the firstlens providing better visual acuity for objects at infinity than thesecond lens and the second lens providing better visual acuity fromintermediate to near distance than the first lens.
 29. An ophthalmiclens system as defined in claim 27 wherein the second baseline diopterpower is more myopic than the first baseline power.
 30. An ophthalmiclens system as defined in claim 27 wherein the second baseline diopterpower is for intermediate distance correction.
 31. An ophthalmic lenssystem as defined in claim 27 wherein the best visual acuity provided bythe second lens is for objects at intermediate distances.
 32. Anophthalmic lens system for improving the vision of a patient comprising:a first multifocal ophthalmic lens for use with one eye of a patient,the first lens having a first baseline diopter power and being biasedfor distance vision; a second multifocal ophthalmic lens for use withthe other eye of the patient, the second lens having a second baselinediopter power different from the first baseline diopter power and beingbiased for intermediate vision; and each of the first and second lensesbeing adapted for implantation in an eye or to be disposed on or in thecornea.
 33. An ophthalmic lens system as defined in claim 32 whereineach of said lenses is an intraocular lens.
 34. A method of correctingthe vision of a patient comprising: placing first and second multifocalophthalmic lenses on or in the eyes of the patient, respectively, withthe first lens having a first baseline diopter power for distance visioncorrection and providing better visual acuity for objects at infinitythan the second lens, the second lens having a second baseline diopterpower for other than distance vision correction providing better visualacuity from intermediate to near distances than the first lens and themaximum power of the second lens being less than the add power requiredfor near vision correction.
 35. A method as defined in claim 34 whereinthe second baseline diopter power is more myopic than the first baselinepower.
 36. A method as defined in claim 34 wherein the second baselinediopter power is for intermediate distance correction.
 37. A method asdefined in claim 34 wherein the first and second lenses are intraocularlenses and the step of placing includes implanting the first and secondlenses in the eyes, respectively, of the patient.
 38. A method asdefined in claim 37 wherein the step of implanting is carried outwithout removing the natural lenses of the eyes of the patient wherebythe patient retains some accommodation.
 39. A method as defined in claim34 wherein the step of placing includes placing the first and secondlenses on or in the corneas, respectively, of the patient.
 40. A methodof correcting the vision of a patient comprising: implanting first andsecond intraocular lenses having different baseline diopter powers inthe eyes, respectively, without removing the natural lenses of thepatient with each of the first and second lenses having a power whichchanges along a power curve, the power curve of the first lens beingsubstantially similar to the power curve of the second lens.
 41. Amethod of correcting the vision of a patient comprising: placing firstand second ophthalmic lenses on or in the eyes of the patient, the firstand second lenses having different baseline diopter powers, the firstlens being biased for distance vision for the patient and the secondlens being biased for intermediate vision.
 42. A method as defined inclaim 41 wherein the first and second lenses are intraocular lenses andthe step of placing includes implanting the first and second lenses inthe eyes, respectively, of the patient.
 43. A method as defined in claim42 wherein the step of implanting is carried out without removing thenatural lenses of the eyes of the patient whereby the patient retainssome accommodation.